一种允许对存储库进行动态过滤/查询的体系结构<SomeDomainModel>

Question

I'm looking for a solid architecture that will solve the following problem:

As a user i want to dynamically filter some database of Persons, by dynamically adding criterias. I also want to be able to batch-update only chosen fields to the database, based on the results of the filter.

The following is true:

• I have a 3-tiered solution (GUI, Business Layer, Data Access Layer).
• Suppose I have a Repository<Person> , the Person is the domain model.
• The repository supports linq and can give me: IQueryable<T> GetAll()

I got some ideas:

• I'm thinking of using Dynamic Expression API, which extends LINQ functionality so i can dynamically add search criterias.
• I've looked at NHibernate QueryBuilder, and that might be something to borrow ideas from.

Solution Theories:
So, anyway I'm thinking of the GUI asking the DomainModel to describe itself (what properties exists, and what operators are allowed, and what are the allowed valuetypes) That way, I could render some cascading dropdowns for the properties and allowed operators. I'm thinking of describing properties either from a method in the Model, for example: DescribeMyself(); And then combining this with decorating the properties with Attributes.

Questions:
So what about describing properties for a Model, how would you do that? For example, the property: string Name , should be searchable with either an operator of Equals , or an operator of Like.
What about enums ? Imagine MyGenderEnum Gender . When doing an Equals filter, i need to describe that it must be matched to either of any value in the given Enum.

Something to think about!

Answer 1

That's a rather broad question.

Just some points:

• Dynamically adding search criteria to an IQueryable<T> is supported out of the box. Just add a call to Where for each criteria:

  repository.GetAll<Person>().Where(x => criteria1(x)).Where(x => criteria2(x));

• Making the model describe itself is something I wouldn't do. I would create a new class, similar to Fluent NHibernates ClassMap<T> or Fluent Validations AbstractValidator<T> .